This invention relates to a system for transmission of signals, and more particularly for transmission of audio voltage signals.
Audio voltage signals produced by audio or audio visual devices are transmitted by various methods. In certain devices like radio player and television set, there are provided with external audio receptacles or jacks to which a length of electric cable and earphones are electrically connected. Audio voltage signals are then transmitted thereof and heard by discrete listeners without causing noise disturbances to the surrounding.
In order to provide such a transmission facility, it is known that audio output voltage of said electrical audio devices operating with AC mains have to be stepped down by means of audio transformers before the audio receptacles or jacks are electrically connected externally.
In another prior art, audio output voltages are isolated by installation of coils between the AC mains and integrated circuits of said devices.
The above prior arts have been somewhat unreliable due to possible electrical hazards caused by breakdown of said audio transformers. There are also incidences in which a relatively minor component failure may cause other components to be overdriven and burned out thereby causing complete failure and direct electrical leakage to chasis of said devices. Under such circumstances, the audio jacks are extremely dangerous for use.
Due to the above mentioned and related deficiencies, it has been a burden for manufacturers concerned to provide facilities in said devices for transmission of audio signals. Therefore, it is not uncommon that transmission facilities are not found in certain audio or audio visual devices.
However, the necessity for transmission of audio voltage signals remains. Whence transmission facilities are not provided, unscupulous practices take place to install various means of transmission to satisfy the needs of individual users.
These installations are more than often in violation to regulations set by the National Electricity Board and Telecommunication Department.
It is therefore the primary object of the present invention to provide a system for transmission of audio signals produced by audio or audio visual devices free of the above electrical hazards caused either by failure of audio transformers or other electrical components. The proposed transmission system also has an economic advantage because no installation of audio transformers is required.
Another object of the present invention is to provide a transmission system easily to be regulated according to rules set by the appropriate authorities.
It is still another object of the present invention to provide a transmission system wherein all electrical parts and antenna for transmission are properly insulated and non-accessible during operative mood. Keeping said components of the transmission system out of contact with the body of users and other conductive surfaces improves the effect of transmission.
From the foregoing, it is yet another important object of the present invention to provide a transmission system adapted for use on conventional audio or audio visual devices with minimum technical modifications to said devices.